Height and width detectors are associated with railroad cars, in order to detect whether the railroad cars follow a prefixed profile. This way the railroad car that is out of the prefixed profile may be stopped before it causes damage to any infrastructure like a tunnel or bridge. Known height and width detectors include two types of detection methods, or a combination thereof. One method is to attach a wire between two poles at specific height and dimensions. The wires are connected to a battery and relay, to form a circuit. When the wire breaks, the circuit is broken, and an alarm is generated which indicates a possible deviation of the railroad car from the prefixed profile. Such height and width detectors rely on a battery and current to indicate if the wire is broken. In some situations, a broken wire may land on a track on which the railroad car operates or on other conductive sources, and create a closed circuit, thus indicating that the wire is not broken when indeed it is, which may create potential safety concerns.
Another detection method used by current height and width detectors include the use of Infrared (IR) beams. If a part of the railroad car breaks the IR beam, an alarm is generated which is indicative of a possible deviation of the railroad car from the prefixed profile. The detection methods using the IR beam are susceptible to false alarms. For example, if the railroad car has a loose canopy that is flapping in the wind and breaks the IR beam, this can create a false alarm.
U.S. Pat. No. 2,366,152 describes a system to detect high and wide cars or open top ladings which exceed the permissible clearances through tunnels, under bridges, etc.